Affiliations: Houston, TX
Drs. Varon and Fromm are Associate Professors of Medicine, Baylor College of Medicine.,
Dr. Marik is Professor of Medicine, University of Pittsburgh Medical Center.
Correspondence to: Joseph Varon, MD, FCCP, 2219 Dorrington, Houston, TX 77030; e-mail: firstname.lastname@example.org
The increasing prevalence of asthma has paralleled an increase in acute asthma exacerbations and asthma morbidity. This is reflected by the occurrence of > 1.8 million emergency department (ED) visits for asthma in the United States annually, leading to nearly 500,000 hospitalizations.1 Because of the significant morbidity and economic costs, clinicians are constantly searching for new interventions with which to treat acutely ill patients as well as more effective ways of using existing agents.
β-Agonists are used as the standard first-line therapy for patients with asthma exacerbations presenting to the ED. The delivery of these agents by inhalation produces a rapid onset of action and has been found to minimize the incidence of systemic side effects. Even though β2-agonists are used universally to treat patients with acute bronchospasm, a number of issues regarding administration remain controversial and unresolved. Surprisingly, these include fundamental questions such as dosage, frequency of administration, use of continuous vs intermittent treatments, and even the mode of administration. A standard dose of a nebulized β2-agonist recommended by the National Asthma Education and Prevention Program guidelines2 in acutely ill adults would be 2.5 to 5 mg albuterol or its equivalent via inhaled nebulizer every 20 min for the first hour of emergent treatment, and every hour thereafter for the next few hours or until the patient is discharged from the acute care setting.
IV β2-agonists or subcutaneous epinephrine have been recommended in patients with severe asthma when the inhaled route is not practical, for example, in uncooperative children, and in patients who are coughing excessively, are too weak to inspire adequately, or are moribund.2–3 Despite the concern of many practitioners with this route of administration, significant complications are uncommon. Cydulka and coworkers4have described the use of subcutaneous epinephrine in 95 patients. Most of their patients showed significant improvement in peak expiratory flow rate values with few side-effects and no “cardiac toxicity.” Chiang and coworkers5 found no clinically significant cardiomyocyte toxicity from the use of IV terbutaline in pediatric patients, as measured by serum troponin level elevations.
In this issue of CHEST (see page 1200), Travers and coauthors conducted a meta-analysis of randomized controlled trials to determine the benefit of therapy with IV β2-agonists for patients with acute severe asthma in the ED. After analyzing the data of this carefully designed meta-analysis, the authors concluded that “evidence is lacking to support the use of IV β2-agonists in ED patients with severe asthma.”
Should we follow the recommendations of Travers and coworkers when dealing with a critically ill patient with severe asthma in the ED? Clearly, inhaled β2-agonists are more effective in reversing airway obstruction in patients with acute severe asthma than are IV sympathomimetics.6–7 Furthermore, there appears to be a minimal incremental benefit from the addition of IV β2-agonists to the regimens of patients receiving adequate doses of inhaled β2-agonists. Although the evidence is lacking for this subset of patients, the administration of IV β2-agonists or subcutaneous epinephrine may have a role in the treatment of patients with severe refractory asthma after, of course, proper trials of high-dose inhaled corticosteroids, inhaled anticholinergic agents, and noninvasive positive-pressure ventilation have been conducted.10 Newer β2-agonists such as inhaled levalbuterol (an R-isomer of racemic albuterol) should be tried as well in these patients as these agents are potent bronchodilators with a better therapeutic index than racemic albuterol and may have a role in the treatment of patients with severe life-threatening asthma.11
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